What happens if someone gets bitten by a black widow? Do they need to go to er? I'm just asking in general.

Maybe. A black widow bite is rarely lethal, but may be serious in the very young, very old, and those with high blood pressure. If you begin to notice swelling, reddness, intense pain, stiffness, chiles, fever, nausea, vomiting, or severe abdominal pain, go to the er immediately. Otherwise, wash the area with soap / water and call your family doctor or local poison control.
Absolutely! A black widow bite is nothing to trifle with; the venom can kill you. Don't go to an er, call an ambulance!